1. Field of the Invention
Priority is claimed on Japanese Patent Applications Nos. 2003-398918 and 2004-138321, filed Nov. 28, 2003 and May 7, 2004, respectively, the contents of which are incorporated herein by reference.
The present invention relates to a reaction gas supply apparatus for a fuel cell, having a regulator to which is applied a cathode inlet pressure of the fuel cell as a reference pressure, to thereby regulate an anode supply pressure of the fuel cell. The present invention also relates to a reaction gas supply method for a fuel cell.
2. Description of Related Art
As an example of a fuel cell system mounted on a fuel cell powered vehicle, a system is known in which oxidant gas is supplied to a cathode electrode of the fuel cell while fuel gas is supplied to an anode electrode of the fuel cell, and power generation output is acquired from an electrochemical reaction of these gases.
Incidentally, when generating electricity using a fuel cell, a difference between pressures of the anode electrode and the cathode electrode (inter-electrode pressure difference) needs to be maintained within a constant range. Therefore, there is a system having a regulator to which is applied the cathode inlet pressure of the fuel cell as a reference pressure, to thereby regulate the anode supply pressure of the fuel cell. For example, in Japanese Patent Application Unexamined Publication No. 2002-373682, a technique is proposed in which the pressure applied to the cathode electrode is controlled by a control apparatus in order to be able to automatically regulate the pressure applied to the anode electrode through the regulator.
Incidentally, there are various operating states of a vehicle, such as a full load output state that delivers full load output, or an idle-stop state. The generated power that is required of a fuel cell fluctuates depending on the state of the vehicle, and the required pressure of the reaction gases also fluctuates accordingly. However, it is difficult to quickly control the anode pressure to an appropriate value (target value) for the cathode pressure over the total power generating range, simply by performing mechanical control using a regulator, so that there is a problem in terms of responsiveness. Also, the existing technology employs a mechanical valve as a regulator, and the anode electrode pressure is regulated in accordance with the response characteristic thereof. Therefore, in a transient state where the amount of gas required for power generation fluctuates, there has been a problem in that there is a delay in the response of the mechanical valve, so that the anode electrode pressure regulated by the regulator deviates from the target value, and control for regulating the pressure to the target value becomes difficult.